#include<stdio.h>

int flag = 0;

int Sum(int s, int e)
{
    int ret = 0;
    for(int i = s; i <= e; i++)
    {
        ret += i;
    }
    return ret*flag;
}



int main()
{
    int start = 1;
    int end = 100;

    printf("I will begin\n");
    int result = Sum(start, end);
    printf("running done, result is: [%d-%d] = %d\n", start, end, result);




    return 0;
}
